The carbohydrate-conversion industry is large. Currently, about 100 million tons of carbohydrates are fermented annually. Much of this fermentation produces fuel-grade ethanol.
Millions of tons of carbohydrates are also fermented every year to provide food and feed products, such as citric acid and lysine.
Fermentation of carbohydrates also produces other products, such as monomers for the polymer industry, e.g. lactic acid for the production of polylactide.
Carbohydrate conversion is an attractive and environmentally-friendly process since carbohydrates are a renewable resource. For example sucrose can be produced from sugar canes and glucose can be produced from corn and wheat starches. However, sugar cane, corn and wheat are produced primarily for human consumption and/or as livestock feed. Increased consumption by industry may impact food costs.
As an alternative, many renewable non-food resources are potential sources of carbohydrates. The renewable non-food resources can generally be described as “woody materials” or “lignocellulosic materials”. These lignocellulosic materials include, but are not limited to, wood and by-products of wood processing (e.g. chips, sawdust, and shavings) as well as residual plant material from agricultural products and paper and paper industry byproducts (e.g. cellulose containing residues and/or paper pulp).
Residual plant material from agricultural products includes processing by-products and field remains.
Processing by-products include, but are not limited to, corn cobs, sugar cane bagasse, sugar beet pulp, empty fruit bunches from palm oil production, straw (e.g. wheat or rice), soy bean hulls, residual meals from the vegetable oil industry (e.g. soybean, peanut, corn or rapeseed), wheat bran and fermentation residue from the beer and wine industries.
Field remains include, but are not limited to, corn stover, post-harvest cotton plants, post-harvest soybean bushes and post-harvest rapeseed plants.
Lignocellulosic materials also include “energy crops” such as switch grass and broom grass which grow rapidly and generate low-cost biomass specifically as a source of carbohydrates.
These lignocellulosic carbohydrate sources contain cellulose, hemicellulose and lignin as their main components can also contain mineral salts (ashes) and lipophilic organic compounds, such as tall oils resin acids, fatty acids, triglycerides and other organic compounds, including volatile organic compounds such as turpentine. The degree and type of these non-carbohydrate materials can create technical problems in production of soluble carbohydrates.